U.S. patent number 10,152,998 [Application Number 14/280,343] was granted by the patent office on 2018-12-11 for features maps of articles with polarized light.
This patent grant is currently assigned to Seagate Technology LLC. The grantee listed for this patent is SEAGATE TECHNOLOGY LLC. Invention is credited to Joachim Walter Ahner, David M. Tung.
United States Patent |
10,152,998 |
Tung , et al. |
December 11, 2018 |
Features maps of articles with polarized light
Abstract
Provided herein is an apparatus including an imaging lens
assembly configured to collect reflected light from a surface of an
article; an image sensor configured to receive reflected light from
the imaging lens assembly, wherein the imaging lens assembly and
the image sensor are each arranged at different angles for focusing
on substantially an entire surface of an article; and a processing
means configured to process signals from the image sensor
corresponding to polarized reflected light and subsequently
generate one or more features maps.
Inventors: |
Tung; David M. (Livermore,
CA), Ahner; Joachim Walter (Livermore, CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
SEAGATE TECHNOLOGY LLC |
Cupertino |
CA |
US |
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Assignee: |
Seagate Technology LLC
(Cupertino, CA)
|
Family
ID: |
54209539 |
Appl.
No.: |
14/280,343 |
Filed: |
May 16, 2014 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20150285743 A1 |
Oct 8, 2015 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61976496 |
Apr 7, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01N
21/8806 (20130101); G01N 21/95 (20130101); G11B
20/1816 (20130101); G01N 21/55 (20130101); G01N
21/21 (20130101); G01B 9/02 (20130101); G01N
2021/8848 (20130101); G01N 2201/06113 (20130101); G01N
21/9506 (20130101); G01N 21/9501 (20130101); G01B
2290/70 (20130101) |
Current International
Class: |
G01N
21/88 (20060101); G01N 21/21 (20060101); G11B
20/18 (20060101); G01N 21/95 (20060101); G01N
21/55 (20140101); G01B 9/02 (20060101) |
Field of
Search: |
;356/364-369,445,237.1,237.2,237.4,237.5
;250/231.11,201.6,548.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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4304815 |
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Aug 1994 |
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DE |
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10049382 |
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Apr 2002 |
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DE |
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2538172 |
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Dec 2012 |
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EP |
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2013029438 |
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Feb 2013 |
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JP |
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WO 2012042944 |
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Apr 2012 |
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WO |
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Other References
International Search Report and Written Opinion dated Jun. 26, 2015
in International Application No. PCT/US2015/020632. 15 pages. cited
by applicant .
PCT International Preliminary Report on Patentability (Chapter I)
dated Oct. 20, 2016 in International Application No.
PCT/US2015/020632. 16 pages. cited by applicant.
|
Primary Examiner: Nguyen; Sang H
Parent Case Text
CROSS REFERENCE
This application claims the benefit of U.S. Provisional Patent
Application No. 61/976,496, filed Apr. 7, 2014.
Claims
What is claimed is:
1. An apparatus, comprising: an imaging lens assembly, including a
lens configured to collect a polarized reflected light from an
entire surface of an article; an image sensor configured to receive
the polarized reflected light from the lens of the imaging lens
assembly, wherein the imaging lens assembly and the image sensor
are each arranged at different angles for focusing on substantially
the entire surface of the article; and a processing means
configured to process signals from the image sensor corresponding
to the polarized reflected light and subsequently generate one or
more feature maps.
2. The apparatus of claim 1, wherein the lens of the imaging lens
assembly comprises a telecentric lens, and wherein the image sensor
comprises at least about 5.5 megapixels.
3. The apparatus of claim 1, wherein the apparatus is configured to
provide one of the p-polarized reflected light or the s-polarized
reflected light to the image sensor at a time.
4. The apparatus of claim 1, wherein the image sensor comprises a
first image sensor at an angle to a second image sensor, wherein
the apparatus is configured to provide one of the p-polarized
reflected light or the s-polarized reflected light to the first
image sensor, and wherein the apparatus is configured to provide
the other one of the p-polarized reflected light or the s-polarized
reflected light to the second image sensor at the same time or a
different time.
5. The apparatus of claim 1, further comprising: a lighting lens
assembly configured to receive light from a light source, wherein
the light source and the lighting lens assembly are each arranged
at different angles for uniformly illuminating substantially the
entire surface of the article.
6. The apparatus of claim 5, wherein the imaging lens assembly and
the image sensor are each arranged at different angles in
accordance with the Scheimpflug principle, and wherein the light
source and the lighting lens assembly are each arranged at
different angles in accordance with the Scheimpflug principle.
7. The apparatus of claim 5, wherein the light source comprises a
first light source at an angle to a second light source, wherein
the first light source is configured to provide one of the
p-polarized incident light, the s-polarized incident light, or the
q-polarized incident light, and wherein the second light source is
configured to provide any other one of the p-polarized incident
light, the s-polarized incident light, or the q-polarized incident
light at the same time or a different time.
8. The apparatus of claim 1, wherein the apparatus is configured to
maintain a linear and an angular position of an article while
imaging the surface of the article.
9. The apparatus of claim 1, wherein the one or more features maps
are generated from different combinations of the polarized incident
light and the polarized reflected light, wherein the polarized
incident light is selected from the p-polarized incident light, the
s-polarized incident light, and the q-polarized incident light, and
wherein the polarized reflected light is selected from the
p-polarized reflected light and the s-polarized reflected
light.
10. The apparatus of claim 1, wherein the features of the one or
more features maps are selected from a thickness of one or more
layers of a hard disk or a workpiece thereof; a homogeneity of one
or more layers of the hard disk or the workpiece thereof; and one
or more stains in one or more layers of the hard disk or the
workpiece thereof.
11. An apparatus, comprising: a lighting lens assembly configured
to receive a light from a light source, wherein the light source
and the lighting lens assembly are each arranged at different
angles for illuminating substantially an entire surface of an
article; an imaging lens assembly, including a lens configured to
collect a reflected light from the entire surface of the article;
an image sensor configured to receive the reflected light from the
lens of the imaging lens assembly, wherein the imaging lens
assembly and the image sensor are each arranged at different angles
for focusing on substantially the entire surface of the article;
and a processing means configured to process signals from the image
sensor corresponding to a polarized reflected light and
subsequently generate one or more features maps.
12. The apparatus of claim 11, wherein the one or more features
maps are generated from different combinations of a polarized
incident light and the polarized reflected light, wherein the
polarized incident light is selected from a p-polarized incident
light, an s-polarized incident light, and a q-polarized incident
light, and wherein the polarized reflected light is selected from a
p-polarized reflected light and an s-polarized reflected light.
13. An apparatus, comprising: a lighting lens assembly configured
to receive a light from a first light source and second light
source at an angle to the first light source, wherein the light
sources and the lighting lens assembly are each arranged at
different angles for illuminating substantially an entire surface
of an article; an imaging lens assembly, including a lens,
configured to collect a reflected light from the entire surface of
the article; a first image sensor at an angle to a second image
sensor configured to receive the reflected light from the lens of
the imaging lens assembly, wherein the imaging lens assembly and
the image sensors are each arranged at different angles for
focusing on substantially the entire surface of the article; and a
processing means configured to process signals from the image
sensors corresponding to a polarized reflected light and
subsequently generate one or more features maps.
14. The apparatus of claim 13, wherein the one or more features
maps are generated from different combinations of a polarized
incident light and the polarized reflected light, wherein the
polarized incident light is selected from a p-polarized incident
light, an s-polarized incident light, and a q-polarized incident
light, and wherein the polarized reflected light is selected from a
p-polarized reflected light and an s-polarized reflected light.
15. The apparatus of claim 14, wherein the first light source is
configured to provide one of the p-polarized incident light, the
s-polarized incident light, or the q-polarized incident light, and
wherein the second light source is configured to provide any other
one of the p-polarized incident light, the s-polarized incident
light, or the q-polarized incident light at the same time or a
different time.
Description
BACKGROUND
An article may be inspected for features such as defects that might
degrade the performance of the article or a system including the
article. For example, a hard disk for a hard disk drive may be
fabricated and inspected for defects that might degrade the
performance of the hard disk or the hard disk drive. Accordingly,
apparatuses and methods may be used to inspect articles for
features.
SUMMARY
Provided herein is an apparatus including an imaging lens assembly
configured to collect reflected light from a surface of an article;
an image sensor configured to receive reflected light from the
imaging lens assembly, wherein the imaging lens assembly and the
image sensor are each arranged at different angles for focusing on
substantially an entire surface of an article; and a processing
means configured to process signals from the image sensor
corresponding to polarized reflected light and subsequently
generate one or more features maps.
These and various other features and advantages will be apparent
from a reading of the following detailed description.
DRAWINGS
FIG. 1A provides a schematic illustrating p-polarized incident
light upon a surface of an article according to one or more
aspects.
FIG. 1B provides a schematic illustrating s-polarized incident
light upon a surface of an article according to one or more
aspects.
FIG. 1C provides a schematic illustrating q-polarized incident
light upon a surface of an article according to one or more
aspects.
FIG. 1D provides a schematic illustrating p-polarized reflected
light from a surface of an article according to one or more
aspects.
FIG. 1E provides a schematic illustrating s-polarized reflected
light from a surface of an article according to one or more
aspects.
FIG. 1F provides a schematic illustrating q-polarized reflected
light from a surface of an article according to one or more
aspects.
FIG. 2A provides a schematic illustrating p-polarized incident
light upon a surface of an article and p-polarized reflected light
selected from mixedly polarized reflected light from the surface of
the article according to one or more aspects.
FIG. 2B provides a schematic illustrating p-polarized incident
light upon a surface of an article and s-polarized reflected light
selected from mixedly polarized reflected light from the surface of
the article according to one or more aspects.
FIG. 2C provides a schematic illustrating s-polarized incident
light upon a surface of an article and s-polarized reflected light
selected from mixedly polarized reflected light from the surface of
the article according to one or more aspects.
FIG. 2D provides a schematic illustrating s-polarized incident
light upon a surface of an article and p-polarized reflected light
selected from mixedly polarized reflected light from the surface of
the article according to one or more aspects.
FIG. 3A provides a schematic illustrating detection of features of
articles according to one or more aspects.
FIG. 3B provides a schematic illustrating detection of features of
articles according to one or more aspects.
FIG. 4 provides an image of a surface of an article with one or
more features including defects according to one or more
aspects.
DESCRIPTION
Before some particular embodiments are described and/or illustrated
in greater detail, it should be understood by persons having
ordinary skill in the art that the particular embodiments described
and/or illustrated herein do not limit the concepts provided
herein, as features in such particular embodiments may vary. It
should likewise be understood that a particular embodiment
described and/or illustrated herein has features that may be
readily separated from the particular embodiment and optionally
combined with or substituted for features in any of several other
embodiments described and/or illustrated herein.
It should also be understood by persons having ordinary skill in
the art that the terminology used herein is for the purpose of
describing some particular embodiments, and the terminology does
not limit the concepts provided herein. Unless indicated otherwise,
ordinal numbers (e.g., first, second, third, etc.) are used to
distinguish or identify different elements or steps in a group of
elements or steps, and do not supply a serial or numerical
limitation. For example, "first," "second," and "third" elements or
steps need not necessarily appear in that order, and embodiments
need not necessarily be limited to the three elements or steps. It
should also be understood that, unless indicated otherwise, any
labels such as "left," "right," "front," "back," "top," "bottom,"
"forward," "reverse," "clockwise," "counter clockwise," "up," and
"down," or other similar terms such as "upper," "lower," "aft,"
"fore," "vertical," "horizontal," "proximal," and "distal," or the
like, are used for convenience and are not intended to imply, for
example, any particular fixed location, orientation, or direction.
Instead, such labels are used to reflect, for example, relative
location, orientation, or direction. It should also be understood
that the singular forms of "a," "an," and "the" include plural
references unless the context clearly dictates otherwise.
Unless defined otherwise, all technical and scientific terms used
herein have the same meaning as commonly understood by persons
having ordinary skill in the art.
An article may be inspected for features including defects (e.g.,
surface and/or subsurface defects) that might degrade the
performance of the article or a system including the article. The
article may include any article of manufacture or a workpiece
thereof in any stage of manufacture having one or more surfaces
operable to specularly reflect light. For example, the article may
include, but is not limited to, a semiconductor wafer, a magnetic
recording medium (e.g., a hard disk for a hard disk drive), or a
workpiece thereof in any stage of manufacture.
A hard disk or a workpiece thereof may be inspected for features
including defects (e.g., surface and/or subsurface defects) that
might degrade the performance of the hard disk or the hard disk
drive. For example, hard disks or workpieces thereof may be
inspected for stains. For example, hard disks or workpieces thereof
having a lubricant layer may be inspected for lubricant layer
inhomogeneity including lubricant layer smears, ripples, bumps,
and/or depletion. For example, hard disks or workpieces thereof
having a carbon overcoat layer may be inspected for carbon overcoat
inhomogeneity including carbon overcoat layer voids and/or shadows
(e.g., shadows from sputtering clamps).
It is important to inspect articles for features including
performance-degrading defects to correct manufacturing trends and
to increase product quality. Provided herein are apparatuses and
methods for inspecting articles for features including detecting,
mapping, and/or distinguishing features of articles, which features
include, but are not limited to, defects.
Apparatuses and methods for inspecting articles for features employ
various forms of polarized light for detecting, mapping, and/or
distinguishing features of articles.
FIGS. 1A-1C provide schematics illustrating some of the various
forms of polarized incident light for incident light upon a surface
of an article. As shown in each of FIGS. 1A-1C, a plane of
incidence may be formed between incident light hv or a ray thereof
and a surface normal N to a surface of an article 100 at a point P
at which the incident light or ray is incident.
FIG. 1A provides a schematic illustrating p-polarized incident
light upon a surface of an article. When incident light is linearly
polarized such that the electric field of the incident light is
parallel to the plane of incidence, the incident light may be
described as p-polarized incident light.
FIG. 1B provides a schematic illustrating s-polarized incident
light upon a surface of an article. When incident light is linearly
polarized such that the electric field of the incident light is
perpendicular to the plane of incidence, the incident light may be
described as s-polarized incident light.
FIG. 1C provides a schematic illustrating q-polarized incident
light upon a surface of an article. When incident light is linearly
polarized such that the electric field of the incident light is
45.degree. to the plane of incidence, the incident light may be
described as q-polarized incident light. It should be understood
that one of two forms of q-polarized incident light is shown.
As further shown in FIGS. 1A-1C, an angle of incidence
.alpha..sub.1 may be formed between the incident light or ray and
the surface normal. A glancing angle .beta..sub.1 may be formed
between the incident light or ray and the surface of the article.
The glancing angle may also be described as an altitudinal angle
between the incident light or ray and the surface of the article.
The angle of incidence and the glancing angle are complementary
angles.
FIGS. 1D-1F provide schematics illustrating some of the various
forms of polarized reflected light for reflected light from a
surface of an article. As shown in each of FIGS. 1D-1F, a plane of
reflection may be formed between reflected light or a ray thereof
and a surface normal N to a surface of an article 100 at a point P
at which the reflected light or ray is reflected.
FIG. 1D provides a schematic illustrating p-polarized reflected
light from a surface of an article. When the reflected light is
linearly polarized such that the electric field of the reflected
light is parallel to the plane of reflection, the reflected light
may be described as p-polarized reflected light.
FIG. 1E provides a schematic illustrating s-polarized reflected
light from a surface of an article. When the reflected light is
linearly polarized such that the electric field of the reflected
light is perpendicular to the plane of reflection, the reflected
light may be described as s-polarized reflected light.
FIG. 1F provides a schematic illustrating q-polarized reflected
light from a surface of an article. When the reflected light is
linearly polarized such that the electric field of the reflected
light is 45.degree. to the plane of reflection, the reflected light
may be described as q-polarized reflected light. It should be
understood that one of two forms of q-polarized reflected light is
shown.
As further shown in FIGS. 1D-1F, an angle of reflection
.alpha..sub.2 may be formed between the reflected light or ray and
the surface normal. An angle .beta..sub.2 may be formed between the
reflected light or ray and the surface of the article. The angle of
reflection and the angle .beta..sub.2 are complementary angles. The
angle of reflection and the angle of incidence are equal or
congruent angles. The angle .beta..sub.2 and the glancing angle are
equal or congruent angles.
FIGS. 2A-2D provide schematics illustrating some combinations of
polarized incident light and polarized reflected light for
inspecting articles for features. As shown in each of FIGS. 2A-2D,
polarized incident light hv or a ray thereof may be specularly
reflected from one or more surfaces of an article 200. The one or
more surfaces of the article may respectively correspond to one or
more layers of the article including, but not limited to, one or
more layers selected from a first layer 202, a second layer 204,
and a third layer 206. For example, the article 200 may be a hard
disk or a workpiece thereof, wherein the first layer 202 is a
lubricant layer overlying the second layer 204, wherein the second
layer 204 is a carbon overcoat layer overlying the third layer 206,
and wherein the third layer 206 is a layer stack including at least
a magnetic recording layer. Depending upon characteristics of each
of the one or more layers including composition, dimensions (e.g.,
thickness), and/or features (e.g., defects), the polarized incident
light may be specularly reflected from the one or more surfaces of
the article to provide mixedly polarized reflected light including
p-polarized reflected light, s-polarized reflected light, and
q-polarized reflected light. While not shown in FIGS. 2A-2D, the
mixedly polarized reflected light may further include circularly
polarized light and elliptically polarized light. A reflected
light-selecting means 210 may be used to select a particular
polarized reflected light to effect a desired combination of
polarized incident light and polarized reflected light for
inspecting articles.
FIG. 2A provides a schematic illustrating a combination of
p-polarized incident light upon a surface of an article and
selected p-polarized reflected light from the surface of the
article. As shown, p-polarized incident light may be specularly
reflected from one or more surfaces of an article to provide
mixedly polarized reflected light including at least p-polarized
reflected light, s-polarized reflected light, and q-polarized
reflected. A reflected light-selecting means 210 may be used to
select p-polarized reflected light to effect a combination of
p-polarized incident light and p-polarized reflected light for
inspecting articles.
FIG. 2B provides a schematic illustrating a combination of
p-polarized incident light upon a surface of an article and
selected s-polarized reflected light from the surface of the
article. As shown, p-polarized incident light may be specularly
reflected from one or more surfaces of an article to provide
mixedly polarized reflected light including at least p-polarized
reflected light, s-polarized reflected light, and q-polarized
reflected. A reflected light-selecting means 210 may be used to
select s-polarized reflected light to effect a combination of
p-polarized incident light and s-polarized reflected light for
inspecting articles.
FIG. 2C provides a schematic illustrating a combination of
s-polarized incident light upon a surface of an article and
selected s-polarized reflected light from the surface of the
article. As shown, s-polarized incident light may be specularly
reflected from one or more surfaces of an article to provide
mixedly polarized reflected light including at least p-polarized
reflected light, s-polarized reflected light, and q-polarized
reflected. A reflected light-selecting means 210 may be used to
select s-polarized reflected light to effect a combination of
s-polarized incident light and s-polarized reflected light for
inspecting articles.
FIG. 2D provides a schematic illustrating a combination of
s-polarized incident light upon a surface of an article and
selected p-polarized reflected light from the surface of the
article. As shown, s-polarized incident light may be specularly
reflected from one or more surfaces of an article to provide
mixedly polarized reflected light including at least p-polarized
reflected light, s-polarized reflected light, and q-polarized
reflected. A reflected light-selecting means 210 may be used to
select p-polarized reflected light to effect a combination of
s-polarized incident light and p-polarized reflected light for
inspecting articles.
Apparatuses and methods for inspecting articles for features employ
various combinations of components for detecting, mapping, and/or
distinguishing features of articles.
FIGS. 3A and 3B provide schematics illustrating some of the various
combinations of components for detecting, mapping, and/or
distinguishing features of articles. As shown in each of FIGS. 3A
and 3B, an apparatus 300 may include, but is not limited to, a
lighting side of the apparatus including lighting-side components
and a detecting side of the apparatus including detecting-side
components. The lighting-side components may include, but are not
limited to, a light source assembly 310 and a lighting lens
assembly 320. Depending upon the light source assembly and the
quality of light therefrom, the lighting-side components may
further optionally include one or more lighting optical devices
330. The detecting-side components may include, but are not limited
to, an image sensor assembly 340, an imaging lens assembly 350, and
one or more imaging optical devices 360. The apparatus may further
include a processing means 370. While not shown in FIGS. 3A and 3B,
the apparatus may further include a stage configured to support an
article. The stage may be further optionally configured to rotate
the article, if desired, for piecewise inspection.
Turning to the lighting-side of the apparatus, the light source
assembly 310 and the lighting lens assembly 320 shown in each of
FIGS. 3A and 3B may be optionally positioned at different angles
such that an article plane a corresponding to a surface of an
article, a light source plane b corresponding to a light source of
the light source assembly, and a lens plane c corresponding to a
lighting lens of the lighting lens assembly converge at Scheimpflug
intersection Q. Because the light source assembly and the lighting
lens assembly are positioned at a side of the article for
illuminating the surface the article, it may be important to employ
a Scheimpflug correction in accordance with the Scheimpflug
principle to uniformly illuminate the entire surface of the article
or a predetermined portion thereof. Otherwise, time-intensive
rotation of the article, translation of the article, or both may be
required to uniformly illuminate the entire surface of the article
or the predetermined portion thereof over time. A Scheimpflug
correction may not be needed for the light source assembly and the
lighting lens assembly if the light is sufficiently afocal
therefrom.
It should be understood that uniformly or homogeneously
illuminating an entire surface of an article or a predetermined
portion thereof may include, but is not limited to, subjecting the
entire surface of the article or the predetermined portion thereof
to the same or about the same quantity of light per unit time, the
same or about the same radiant energy per unit time (e.g., radiant
power or radiant flux), or the same or about the same radiant power
per unit area (e.g., irradiance or radiant flux density).
As further shown in each of FIGS. 3A and 3B, the light source
assembly 310 and the lighting lens assembly 320 may be positioned
at a particular distance and/or angle for illuminating a surface an
article. The distance and/or angle may be optimized for one or more
types of features.
The light source assembly 310 and the lighting lens assembly 320
may be positioned for illuminating a surface of an article at an
angle of incidence ranging from greater than 0.degree. to less than
90.degree., wherein an angle of incidence of about 0.degree.
represents illuminating the surface of the article from directly
above the article, and wherein an angle of incidence of about
90.degree. represents illuminating the surface of the article
side-on. In some non-limiting embodiments, for example, the light
source assembly and the lighting lens assembly are positioned for
illuminating the surface of the article at Brewster's angle for one
or more surfaces of the article or one or more types of features
thereof. In such embodiments, illuminating the surface of the
article at Brewster's angle may allow for maximal difference in
p-polarized and s-polarized reflected light for the one or more
surfaces of the article or the one or more types of features
thereof. In some non-limiting embodiments, for example, the light
source assembly and the lighting lens assembly are positioned for
illuminating the surface of the article at an angle other than
Brewster's angle for one or more surfaces of the article or one or
more types of features thereof.
The light source assembly 310 and the lighting lens assembly 320
may be positioned for illuminating a surface of an article at a
glancing angle ranging from greater than 0.degree. to less than
90.degree., wherein a glancing angle of about 0.degree. represents
illuminating the surface of the article side-on, and wherein a
glancing angle of about 90.degree. represents illuminating the
surface of the article from directly above the article. In some
non-limiting embodiments, for example, the light source assembly
and the lighting lens assembly are positioned for illuminating the
surface of the article at a glancing angle greater than 0.degree.,
5.degree., 10.degree., 15.degree., 20.degree., 25.degree.,
30.degree., 35.degree., 40.degree., 45.degree., 50.degree.,
55.degree., 60.degree., 65.degree., 70.degree., 75.degree.,
80.degree., or 85.degree.. In some non-limiting embodiments, for
example, the light source assembly and the lighting lens assembly
are positioned for illuminating the surface of the article at a
glancing angle less than 90.degree., 85.degree., 80.degree.,
75.degree., 70.degree., 65.degree., 60.degree., 55.degree.,
50.degree., 45.degree., 40.degree., 35.degree., 30.degree.,
25.degree., 20.degree., 15.degree., 10.degree., or 5.degree..
Combinations of the foregoing may be used to describe the glancing
angle for illuminating the surface of the article. In some
non-limiting embodiments, for example, the light source assembly
and the lighting lens assembly are positioned for illuminating the
surface of the article at a glancing angle greater than 0.degree.
and less than 90.degree. (i.e., between 0.degree. and) 90.degree.,
including greater than 0.degree. and less than 45.degree. (i.e.,
between 0.degree. and 45.degree.), and including greater than
45.degree. and less than 90.degree. (i.e., between 45.degree. and
90.degree.). Because the glancing angle and the angle of incidence
are complementary angles, it should be understood that the
foregoing may be equally expressed in terms of the angle of
incidence.
The light source assembly 310 may include a light source operable
to provide light for homogeneously illuminating an entire surface
of an article or a predetermined portion thereof.
The light source may be configured to provide light including any
one or more characteristics. The light source may be configured to
provide light including a relatively wide range of wavelengths
(e.g., whole spectrum, broad spectrum, ultraviolet-visible,
visible, infrared, etc.), a relatively narrow range of wavelengths
(e.g., a subdivision of ultraviolet such as UVA, UVB, UVC, etc.; a
subdivision of visible such as red, green, blue, etc.; a
subdivision of infrared such as near infrared, mid-infrared; etc.),
or a particular wavelength (e.g., monochromatic) for homogeneously
illuminating an entire surface of an article or a predetermined
portion thereof. In terms of frequency, the light source may be
configured to provide light including a relatively wide range of
frequencies (e.g., whole spectrum, broad spectrum,
ultraviolet-visible, visible, infrared, etc.), a relatively narrow
range of frequencies (e.g., a subdivision of ultraviolet such as
UVA, UVB, UVC, etc.; a subdivision of visible such as red, green,
blue, etc.; a subdivision of infrared such as near infrared,
mid-infrared; etc.), or a particular frequency (e.g.,
monochromatic) for homogeneously illuminating an entire surface of
an article or a predetermined portion thereof. The light source may
be configured to provide light including unpolarized light or
polarized light for homogeneously illuminating an entire surface of
an article or a predetermined portion thereof, wherein the
polarized light includes linearly polarized light (e.g.,
p-polarized light, s-polarized light, q-polarized light, etc.),
circularly polarized light, or elliptically polarized light. The
light source may be configured to provide light including a certain
degree of spatial and/or temporal coherence ranging from
noncoherent light to coherent light (e.g., laser) for homogeneously
illuminating an entire surface of an article or a predetermined
portion thereof.
One or more lighting optical devices 330 shown in each of FIGS. 3A
and 3B may be used in conjunction with the light source assembly
310 to provide light including any one or more of the
characteristics described herein to a surface of an article. The
one or more lighting optical devices may include, but are not
limited to, one or more lighting optical devices selected from
filters (e.g., polarizers, neutral density filters), compensators
(e.g., retarders such variable retarders or waveplates such as
quarter-wave plates and half-wave plates), and photoelastic
modulators in any desired combination and/or order. The one or more
lighting optical devices may establish a polarization management
device or an incident light-selecting means operable to select a
particular polarized incident light for illuminating a surface of
an article. In some non-limiting embodiments, for example, the
polarization management device or the incident light-selecting
means is operable to select any one of p-polarized incident light,
s-polarized incident light, or q-polarized incident light for
illuminating a surface of an article at any given time.
Turning to the detecting-side of the apparatus, the image sensor
assembly 340 and the imaging lens assembly 350 shown in each of
FIGS. 3A and 3B may be positioned at different angles such that the
article plane a, an image sensor plane d corresponding to an image
sensor of the image sensor assembly, and a lens plane e
corresponding to an imaging lens of the imaging lens assembly
converge at Scheimpflug intersection R. Because the imaging sensor
assembly and the imaging lens assembly are positioned at a side of
the article for detecting specularly reflected light from the
surface of the article, it is important to employ a Scheimpflug
correction in accordance with the Scheimpflug principle to bring
the entire surface of the article into the plane of focus.
Otherwise, only a small portion of the entire surface of the
article would be in the plane of focus at any given time requiring
time-intensive rotation of the article, translation of the article,
or both to bring the entire surface of the article into the plane
of focus over time.
As further shown in each of FIGS. 3A and 3B, the image sensor
assembly 340 and the imaging lens assembly 350 may be positioned at
a particular distance and/or angle for detecting specularly
reflected light from a surface of an article. The distance and/or
angle may be optimized for one or more types of features.
The image sensor assembly 340 and the imaging lens assembly 350 may
be positioned for detecting specularly reflected light from a
surface of an article at an angle of reflection matching the angle
of incidence at which the light source assembly 310 and the
lighting lens assembly 320 are positioned for illuminating the
surface of the article.
The image sensor assembly 340 and the imaging lens assembly 350 may
be positioned for detecting specularly reflected light from a
surface of an article at an angle (e.g., the angle .beta..sub.2 of
FIGS. 1D-1F) matching the glancing angle at which the light source
assembly 310 and the lighting lens assembly 320 are positioned for
illuminating the surface of the article.
The image sensor assembly 340 may include an image sensor operable
to detect specularly reflected light from one or more surfaces of
an article and convert the light into electronic signals for
processing by the processing means 370.
The image sensor may be configured to detect light including any
one or more characteristics. The image sensor may be configured to
detect light including a relatively wide range of wavelengths
(e.g., whole spectrum, broad spectrum, ultraviolet-visible,
visible, infrared, etc.), a relatively narrow range of wavelengths
(e.g., a subdivision of ultraviolet such as UVA, UVB, UVC, etc.; a
subdivision of visible such as red, green, blue, etc.; a
subdivision of infrared such as near infrared, mid-infrared; etc.),
or a particular wavelength (e.g., monochromatic) and convert the
light into electronic signals for processing by the processing
means. In terms of frequency, the image sensor may be configured to
detect light including a relatively wide range of frequencies
(e.g., whole spectrum, broad spectrum, ultraviolet-visible,
visible, infrared, etc.), a relatively narrow range of frequencies
(e.g., a subdivision of ultraviolet such as UVA, UVB, UVC, etc.; a
subdivision of visible such as red, green, blue, etc.; a
subdivision of infrared such as near infrared, mid-infrared; etc.),
or a particular frequency (e.g., monochromatic) and convert the
light into electronic signals for processing by the processing
means. The image sensor may be configured to detect light including
unpolarized light or polarized light and convert the light into
electronic signals for processing by the processing means, wherein
the polarized light includes linearly polarized light (e.g.,
p-polarized light, s-polarized light, q-polarized light, etc.),
circularly polarized light, or elliptically polarized light. The
light source may be configured to detect light including a certain
degree of spatial and/or temporal coherence ranging from
noncoherent light to coherent light (e.g., laser) and convert the
light into electronic signals for processing by the processing
means.
The image sensor may include a number of light sensor elements or
pixels, each of which may include a photodetector and one or more
readout devices (e.g., capacitors, transistors, etc.).
The number of pixels may be arranged in n rows and m columns of a
two-dimensional array, and the number of pixels n.times.m or
resolution may be expressed in millions of pixels or megapixels
("MP"). For example, the number of pixels may be arranged in 2048
rows and 2048 columns of a two-dimensional array, and the number of
pixels 2048.times.2048 may be expressed as 4.2 MP. For example, the
number of pixels may be arranged in 2560 rows and 2160 columns of a
two-dimensional array, and the number of pixels 2560.times.2160 may
be expressed as 5.5 MP. It should be understood that the image
sensor is not limited to the foregoing numbers of pixels as the
image sensor may include more or fewer pixels than either of the
foregoing numbers of pixels.
Each pixel may be a rectangle or square in shape, and each pixel
may be micrometer sized (i.e., admits of .mu.m units as measured)
in at least one of a length or a width. For example, each pixel may
be a rectangle in shape, and each pixel may be about 6.5 .mu.m in
at least one of a length or a width. For example, each pixel may be
a square in shape, and each pixel may be about 6.5 .mu.m in length
and width. It should be understood that the image sensor is not
limited to pixels of the foregoing shapes as the image sensor may
include pixels of any of a number of shapes different than the
foregoing shapes. It should be understood that the image sensor is
not limited to pixels of the foregoing size as the image sensor may
include pixels of any of a number of sizes (e.g., from about 3
.mu.m to about 15 .mu.m) different than the foregoing size.
Each pixel may correspond to a particular, fixed area of a surface
of an article, and each pixel may respectively correspond to a
particular, fixed area of a features map. In other words, there may
be a one-to-one-to-one correspondence between a particular, fixed
area of a surface of an article, a pixel of the image sensor, and a
particular, fixed area of a features map. Such correspondence
facilitates identification of a particular feature's coordinates
about an article for further analysis, optionally with additional
analytical instrumentation. Such correspondence across a number of
articles facilitates identification of article-over-article defects
and correction of manufacturing trends.
The image sensor may include, but is not limited to, a
charge-coupled device ("CCD"), an intensified charge-coupled device
("ICCD"), an electron-multiplying charge-coupled device ("EMCCD"),
a complementary metal-oxide semiconductor ("CMOS"), or a scientific
complementary metal-oxide semiconductor ("sCMOS").
The image sensor assembly 340 may include, but is not limited to, a
CCD camera, an ICCD camera, an EMCCD camera, a CMOS camera, or an
sCMOS camera.
The imaging lens assembly 350 may include a lens operable to
collect specularly reflected light from one or more surfaces of an
article and provide the light to the image sensor assembly 340.
The lens may include, but is not limited to, an objective lens. An
objective lens may include a telecentric lens, which reduces errors
with respect to feature position, and which reduces optical
aberration. For example, the lens may include, but is not limited
to, an object-space telecentric lens (i.e., entrance pupil at
infinity), an image-space telecentric lens (i.e., exit pupil at
infinity), or a double telecentric lens (i.e., entrance and exit
pupils at infinity). It should be understood that the lens is not
limited to the foregoing lenses as the lens may include any of a
number of lenses different than the foregoing lenses.
One or more imaging optical devices 360 shown in each of FIGS. 3A
and 3B may be used in conjunction with the imaging lens assembly
350 to provide light including any one or more of the
characteristics described herein to the image sensor assembly 340.
The one or more imaging optical devices may include, but are not
limited to, one or more imaging optical devices selected from
filters (e.g., polarizers, neutral density filters), compensators
(e.g., retarders such as variable retarders or waveplates such as
quarter-wave plates and half-wave plates), and photoelastic
modulators in any desired combination and/or order. The one or more
imaging optical devices may establish a polarization management
device or a reflected light-selecting means operable to select a
particular polarized reflected light for the image sensor assembly.
In some non-limiting embodiments, for example, the polarization
management device or the reflected light-selecting means is
operable to select any one of p-polarized reflected light,
s-polarized reflected light, or q-polarized reflected light for the
image sensor assembly.
Turning to the processing means of the apparatus, the processing
means 370 shown in each of FIGS. 3A and 3B may include one or more
computers or equivalent devices including primary and/or secondary
memory and one or more processing elements operable to carry out
arithmetic and logical operations. The one or more computers or
equivalent devices may include, but are not limited to, one or more
computers or equivalent devices selected from servers,
workstations, desktop computers, nettops, laptops, netbooks, and
mobile devices including tablets and smartphones. The one or more
computers or equivalent devices may contain graphics processing
units ("GPU"s), application-specific integrated circuits ("ASIC"s),
field-programmable gate arrays ("FPGA"s), etc.
The processing means 370 may include or have access to instructions
for conveying articles to the apparatus; positioning articles for
inspection, optionally including gradationally or continuously
rotating articles for inspection; inserting optical devices into
the incident light path and/or the reflected light path;
positioning optical devices in the incident light path and/or the
reflected light path; tuning optical devices (e.g.,
piezoelectric-based polarization management devices); removing
optical devices from the incident light path and/or the reflected
light path; positioning the light source assembly and the lighting
lens assembly in accordance with the Scheimpflug principle;
positioning the light source assembly and the lighting lens
assembly in accordance with an optimum distance and/or angle for
one or more types of features; switching the light source on and
off or otherwise between modes for providing light and not
providing light; positioning the image sensor assembly and the
imaging lens assembly in accordance with the Scheimpflug principle;
positioning the image sensor assembly and the imaging lens assembly
in accordance with an optimum distance and/or angle for one or more
types of features; switching the image sensor on and off or
otherwise between modes for detecting light and not detecting
light; and/or synchronizing the light source with the image
sensor.
The processing means 370 may include or have access to instructions
for processing electronic signals from the image sensor assembly
340 for detecting, mapping, and/or distinguishing features of
articles. The electronic signals from the image sensor may
correspond to image sensor-detected light resulting from different
selections or combinations of polarized incident light and
polarized reflected light. For example, as shown in FIGS. 2A-2D,
some combinations of polarized incident light and polarized
reflected light include, but are not limited to, p-polarized
incident light and p-polarized reflected light; p-polarized
incident light and s-polarized reflected light; s-polarized
incident light and p-polarized reflected light; and s-polarized
incident light and s-polarized reflected light. It should be
understood that combinations of polarized incident light and
polarized reflected light are not limited to the foregoing
combinations as any of a number of combinations different than the
foregoing may be used. For example, q-polarized incident light
and/or q-polarized reflected light may be used in combinations.
The processing means 370 may generate features maps corresponding
to the electronic signals from the image sensor assembly 340, each
of which features maps may provide differentiating or
distinguishing information for one or more types of features. The
distinguishing information is in accordance with different
combinations of polarized incident light and polarized reflected
light, each of which combinations may interact differently with one
or more types of features. FIG. 4 provides an image of such a
features map 400 including a defect 410.
The processing means 370 may generate any of a number of features
maps corresponding to the electronic signals from the image sensor
assembly 340. For example, the processing means may generate a
features map for a combination of p-polarized incident light and
p-polarized reflected light; p-polarized incident light and
s-polarized reflected light; s-polarized incident light and
p-polarized reflected light; and/or s-polarized incident light and
s-polarized reflected light. Because any of a number of
combinations of polarized incident light and polarized reflected
light different than the foregoing may be used including
q-polarized incident light and/or q-polarized reflected light, the
processing means may generate features maps 400A, 400B, 400C, . . .
, 400n, wherein n indicates the n.sup.th features map for the
n.sup.th desired combination of polarized incident light and
polarized reflected light.
The processing means 370 may generate one or more polarization
contrast maps or composite features maps from any two or more
features maps or the information sufficient to produce them. A
composite features map may enhance one or more types of features
between any two or more features maps. A composite features map may
consolidate one or more types of features onto the composite
features map from any two or more features maps including different
types of features between them. The one-to-one-to-one
correspondence between a particular, fixed area of a surface of an
article, a pixel of the image sensor, and a particular, fixed area
of a features map facilitates generating the one or more composite
features maps.
The processing means 370 may increase pixel resolution for one or
more features map with pixel interpolation. Pixel interpolation may
increase pixel resolution about 10.times. or more without an
increase in pixels in the image sensor.
The apparatus 300 shown in each of FIGS. 3A and 3B may be
configured to inspect articles for features at a rate commensurate
with or greater than the rate at which the articles or workpieces
thereof are produced. In some non-limiting embodiments, for
example, the apparatus is configured to inspect articles at a rate
of at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, or 20
article(s) per second, or greater. Inspecting articles for features
at a rate commensurate with or greater than the rate at which the
articles or workpieces thereof are produced is a function of many
features of the apparatus including, but not limited to,
maintaining the linear and the angular position of articles while
inspecting them.
In view of the foregoing, FIG. 3A provides a schematic illustrating
some embodiments of an apparatus for detecting, mapping, and/or
distinguishing features of articles. As shown in FIG. 3A, an
apparatus 300 may include, but is not limited to, a lighting side
of the apparatus including lighting-side components and a detecting
side of the apparatus including detecting-side components.
The lighting-side components of the apparatus 300 of FIG. 3A may
include, but are not limited to, a light source assembly 310 and a
lighting lens assembly 320, wherein the light source assembly and
the lighting lens assembly are optionally adjusted in accordance
with the Scheimpflug principle.
The light source assembly 310 may include, but is not limited to, a
high-speed flash lamp (e.g., 5 mW-500 W Xe flash lamp) for
minimizing vibration while detecting specularly reflected light
from a surface of an article.
The lighting-side components of the apparatus 300 of FIG. 3A may
optionally include one or more lighting optical devices 330
including, but not limited to, one or more lighting optical devices
selected from a neutral density filter 332, a polarizer 334 (e.g.,
linear polarization filter), and a compensator 336 (e.g., variable
retarder or quarter-wave plate).
The detecting-side components of the apparatus 300 of FIG. 3A may
include, but are not limited to, an image sensor assembly 340, an
imaging lens assembly 350, and one or more imaging optical devices
360, wherein the image sensor assembly and the imaging lens
assembly are adjusted in accordance with the Scheimpflug
principle.
The image sensor assembly 340 may include, but is not limited to,
an sCMOS image sensor.
The imaging lens assembly 350 may include, but is not limited to, a
telecentric lens for reducing feature-position errors and optical
aberrations.
The imaging optical devices 360 may include, but are not limited
to, one or more imaging optical devices selected from a polarizer
364 (e.g., linear polarization filter), and a compensator 366
(e.g., variable retarder or quarter-wave plate).
Features of the processing means 370 of the apparatus 300 of FIG.
3A are described herein.
Also in view of the foregoing, FIG. 3B provides a schematic
illustrating some embodiments of an apparatus for detecting,
mapping, and/or distinguishing features of articles. As shown in
FIG. 3B, an apparatus 300 may include, but is not limited to, a
lighting side of the apparatus including lighting-side components
and a detecting side of the apparatus including detecting-side
components.
The lighting-side components of the apparatus 300 of FIG. 3B may
include, but are not limited to, a light source assembly 310 and a
lighting lens assembly 320, wherein the light source assembly and
the lighting lens assembly are optionally adjusted in accordance
with the Scheimpflug principle.
The light source assembly 310 may include, but is not limited to, a
first light source 312 at an angle to a second light source 314
with a beam-splitting-and-light-trapping assembly 316 therebetween,
wherein the angle is sufficient for optimal beam splitting with the
beam-splitting assembly. The first light source may provide
incident light of a first polarization (e.g., p-polarized incident
light) to the beam-splitting-and-light-trapping assembly, wherein a
beam splitter transmits a portion of the light for illuminating a
surface of an article and reflects a portion of the light to a
light trap. The second light source may provide incident light of a
second polarization (e.g., s-polarized incident light) to the
beam-splitting-and-light-trapping assembly, wherein the beam
splitter reflects a portion of the light for illuminating a surface
of an article and transmits a portion of the light to the light
trap.
The lighting-side components of the apparatus 300 of FIG. 3B may
optionally include one or more lighting optical devices 330
including, but not limited to, one or more lighting optical devices
selected from a neutral density filter 332, a polarizer 334 (e.g.,
linear polarization filter), and a compensator 336 (e.g., variable
retarder or quarter-wave plate).
The detecting-side components of the apparatus 300 of FIG. 3B may
include, but are not limited to, an image sensor assembly 340, an
imaging lens assembly 350, and one or more imaging optical devices
360, wherein the image sensor assembly and the imaging lens
assembly are adjusted in accordance with the Scheimpflug
principle.
The image sensor assembly 340 may include, but is not limited to, a
first image sensor 342 at an angle to a second image sensor 344
with a beam-splitting assembly 346 therebetween, wherein the angle
is sufficient for optimal beam splitting with the beam-splitting
assembly, optionally from about 57.degree. to about 60.degree.. The
beam-splitting assembly may be configured to split specularly
reflected light from a surface of an article into reflected light
of a first polarization (e.g., p-polarized incident light) and
reflected light of a second polarization (e.g., s-polarized
incident light). The beam-splitting assembly may be configured to
provide the light of the first polarization to the first image
sensor and provide the light of the second polarization to the
second image sensor, each of which image sensor may be an sCMOS
image sensor.
The imaging lens assembly 350 may include, but is not limited to, a
telecentric lens for reducing feature-position errors and optical
aberrations.
The imaging optical devices 360 may include, but are not limited
to, one or more imaging optical devices selected from a polarizer
364 (e.g., linear polarization filter), and a compensator 366
(e.g., variable retarder or quarter-wave plate).
Features of the processing means 370 of the apparatus 300 of FIG.
3B are described herein.
As such, provided herein is an apparatus, comprising an imaging
lens assembly configured to collect reflected light from a surface
of an article; an image sensor configured to receive reflected
light from the imaging lens assembly, wherein the imaging lens
assembly and the image sensor are each arranged at different angles
for focusing on substantially an entire surface of an article; and
a processing means configured to process signals from the image
sensor corresponding to polarized reflected light and subsequently
generate one or more features maps. In some embodiments, the
imaging lens assembly comprises a telecentric lens, and the image
sensor comprises at least about 5.5 megapixels. In some
embodiments, the apparatus further comprises a reflected
light-selecting means for selecting a polarized reflected light for
the image sensor, wherein the polarized reflected light is selected
from p-polarized reflected light and s-polarized reflected light.
In some embodiments, the apparatus is configured to provide one of
p-polarized reflected light or s-polarized reflected light to the
image sensor at a time. In some embodiments, the image sensor
comprises a first image sensor at an angle to a second image
sensor, wherein the apparatus is configured to provide one of
p-polarized reflected light or s-polarized reflected light to the
first image sensor, and wherein the apparatus is configured to
provide the other one of p-polarized reflected light or s-polarized
reflected light to the second image sensor at the same time or a
different time. In some embodiments, the apparatus further
comprises a lighting lens assembly configured to receive light from
a light source, wherein the light source and the lighting lens
assembly are each arranged at different angles for uniformly
illuminating substantially an entire surface of an article. In some
embodiments, the imaging lens assembly and the image sensor are
each arranged at different angles in accordance with the
Scheimpflug principle, and the light source and the lighting lens
assembly are each arranged at different angles in accordance with
the Scheimpflug principle. In some embodiments, the apparatus
further comprises an incident light-selecting means for selecting a
polarized incident light for a surface of an article, wherein the
polarized incident light is selected from p-polarized incident
light, s-polarized incident light, and q-polarized incident light.
In some embodiments, the light source comprises a first light
source at an angle to a second light source, wherein the first
light source is configured to provide one of p-polarized incident
light, s-polarized incident light, or q-polarized incident light,
and wherein the second light source is configured to provide any
other one of p-polarized incident light, s-polarized incident
light, or q-polarized incident light at the same time or a
different time. In some embodiments, the apparatus is configured to
maintain a linear and an angular position of an article while
imaging a surface of the article. In some embodiments, the one or
more features maps are generated from different combinations of
polarized incident light and polarized reflected light, wherein the
polarized incident light is selected from p-polarized incident
light, s-polarized incident light, and q-polarized incident light,
and wherein the polarized reflected light is selected from
p-polarized reflected light and s-polarized reflected light. In
some embodiments, the features of the one or more features maps are
selected from thickness of one or more layers of a hard disk or a
workpiece thereof; homogeneity of one or more layers of a hard disk
or a workpiece thereof; and stains in one or more layers of a hard
disk or a workpiece thereof.
Also provided herein is an apparatus, comprising a lighting lens
assembly configured to receive light from a light source, wherein
the light source and the lighting lens assembly are each arranged
at different angles for illuminating substantially an entire
surface of an article; an imaging lens assembly configured to
collect reflected light from a surface of an article; an image
sensor configured to receive reflected light from the imaging lens
assembly, wherein the imaging lens assembly and the image sensor
are each arranged at different angles for focusing on substantially
an entire surface of an article; and a processing means configured
to process signals from the image sensor corresponding to polarized
reflected light and subsequently generate one or more features
maps. In some embodiments, the one or more features maps are
generated from different combinations of polarized incident light
and polarized reflected light, wherein the polarized incident light
is selected from p-polarized incident light, s-polarized incident
light, and q-polarized incident light, and wherein the polarized
reflected light is selected from p-polarized reflected light and
s-polarized reflected light. In some embodiments, the apparatus
further comprises an incident light-selecting means for selecting a
polarized incident light for a surface of an article, wherein the
polarized incident light is selected from p-polarized incident
light, s-polarized incident light, and q-polarized incident light.
In some embodiments, the apparatus further comprises a reflected
light-selecting means for selecting a polarized reflected light for
the image sensor, wherein the polarized reflected light is selected
from p-polarized reflected light and s-polarized reflected light,
and wherein the apparatus is configured to provide one of
p-polarized reflected light or s-polarized reflected light to the
image sensor at a time.
Also provided herein is an apparatus, comprising a lighting lens
assembly configured to receive light from a first light source and
second light source at an angle to the first light source, wherein
the light sources and the lighting lens assembly are each arranged
at different angles for illuminating substantially an entire
surface of an article; an imaging lens assembly configured to
collect reflected light from a surface of an article; a first image
sensor at an angle to a second image sensor configured to receive
reflected light from the imaging lens assembly, wherein the imaging
lens assembly and the image sensors are each arranged at different
angles for focusing on substantially an entire surface of an
article; and a processing means configured to process signals from
the image sensors corresponding to polarized reflected light and
subsequently generate one or more features maps. In some
embodiments, the one or more features maps are generated from
different combinations of polarized incident light and polarized
reflected light, wherein the polarized incident light is selected
p-polarized incident light, s-polarized incident light, and
q-polarized incident light, and wherein the polarized reflected
light is selected from p-polarized reflected light and s-polarized
reflected light. In some embodiments, the first light source is
configured to provide one of p-polarized incident light,
s-polarized incident light, or q-polarized incident light, and the
second light source is configured to provide any other one of
p-polarized incident light, s-polarized incident light, or
q-polarized incident light at the same time or a different time. In
some embodiments, the apparatus further comprises a reflected
light-selecting means for selecting a polarized reflected light for
the image sensor, wherein the polarized reflected light is selected
from p-polarized reflected light and s-polarized reflected light,
wherein the apparatus is configured to provide one of p-polarized
reflected light or s-polarized reflected light to the first image
sensor, and wherein the apparatus is configured to provide the
other one of p-polarized reflected light or s-polarized reflected
light to the second image sensor at the same time or a different
time.
While some particular embodiments have been described and/or
illustrated herein, and while these particular embodiments have
been described and/or illustrated in considerable detail, it is not
the intention for these particular embodiments to limit the scope
of the concepts presented herein. Additional adaptations and/or
modifications may readily appear to persons having ordinary skill
in the art, and, in broader aspects, these adaptations and/or
modifications may be encompassed as well. Accordingly, departures
may be made from the foregoing embodiments without departing from
the scope of the concepts provided herein. The implementations
provided herein and other implementations are within the scope of
the following claims.
* * * * *